He is a military commander, a living legend from the past. One of the Six Great Generals of Qin who were able to stop any attack and crush the enemy. His blood is boiling and always looking for a battlefield to fight on. His name was so frightening that the enemy immediately surrendered once they heard of it.
Ou Ki is a man of exceptional intelligence and strength. He always leads the attack in front of his soldiers, turning them into "demons", as described by the enemies on the battlefield. He has achieved great renown throughout the whole of China, and he was, together with the other 5 great generals of Qin, a part of the "Golden Era".
The Six Great Generals of Qin were all retainers of the 28th King of Qin, King Sho. King Sho gave them the special permission to wage war, should they see the need to, instead of asking for permission. Thus, the Six Great Generals of Qin were picked out by King Sho who had great trust in them.
King Sho had a daughter with one of the palace girls from the Royal Harem, which belonged to the king. At the time, there was chaos in the Royal Harem, with many palace girls being envious of others because of the king taking interest in only a select few. This leads to the killing of many palace girls, a disaster at the time. A specific palace girl was pregant with the king's child, but she was afraid of being killed along with her unborn daughter, so she secretly smuggles the daughter out of the Royal Harem shortly after giving birth. Her mother died in a fire which she most likely set up herself so the news would spread that the child died with her too. She was sent to the Ou Family as a servant, with Ou Ki having been informed of everything. Because of this, Ou Ki did not want to adopt the child as a daughter of the family, as it would arouse suspicion. The child was named Kyou, and she grew up and began falling in love with Ou Ki. She promised Ou Ki that, if she were to conquer 100 cities, they would marry. Ou Ki agreed to this, and from then on, Kyou grew to become a part of The Six Great Generals of Qin. She had exceptional intelligence and strength, laying waste to cities and generals.
At one point, King Sho came to know the fact that they were related. However, he was unable to reveal the truth because it could lead to more babies being smuggled from the Royal Harem.
Kyou had throughout the years believed that Ou Ki had forgotten their promise, but on her campaign to conquer her 100th city, Ou Ki visits her and tells her they would finally be able to fulfill their promise soon. However, before she could complete the campaign, a man by the name of Houken one night came to her sleeping chambers, which was guarded by several hundred elite soldiers. The soldiers spots Houken, and they start to wonder if he is from the enemy headquarters. Before they could react, Houken goes on a rampage and kills his way through all the men, until he is confronted by Kyou herself. They engage in a battle, and Kyou manages to injure Houken. But she is overwhelmed and instead cut down by Houken, leading to her death. Ou Ki arrives at the scene, extremely angered and frustrated. He attacks Houken, cutting Houken's face with his glaive, leading Houken to get knocked out. As it turned out years later, Houken had in fact not died, and was out for Ou Ki.
At one point, he engages in a battle with Houken which he was winning. However, Gi Ka appeared behind him and shot an arrow at his back. At the same time, Houken manages to impale him with his glaive, slaying him with the help of Gi Ka. This leads to Houken questioning if he even won the fight fairly.
Afterwards, Shin jumps on his horse and takes control, so they can escape. A wounded Ou Ki tells Shin to look at the battlefield on top of a generals steed, which helps Shin view the battlefield in a different way, seeing new openings and chances to strike. On their way to a safe spot, they are protected by Ou Ki's soldiers, with many enemies surrounding them. They then finally manage to find a spot free of enemies, and the soldiers all begin crying, seeing their general's state. Ou Ki tells his right hand man, Tou, to forbid anyone from following him to death. A dying Ou Ki tells his last words to Shin, saying he has talent despite being young. He gives his giant glaive to Shin and shortly after, he passes on.
Tropes are everywhere in anime. Perhaps no medium is more dependent on them than this one we love so much, so here are a few thoughts on this seemingly overwhelming subject to serve as a doorway to the complex world of anime tropes.